The present invention relates to a device for controlling cation saturation, especially designed to verify the state of activity of the ion interchanging or exchange resins in drinking water purifying filters, by measuring the cation potential maintained by the resins after a period of use.
Consumers are becoming more and more interested in filters for purifying drinking water, both in those cases in which the water is supplied from a municipal network and in those in which it is supplied by their own means, whether from a well or from a spring. In any event the water should be chlorinated to avoid infections and in the majority of the cases it should be treated with softening agents capable of eliminating excess calcium.
Clearly the purifying filter is an effective and cheap solution since it simultaneously treats the negative points of the water, taste and excessive hardness. The incorporation of biological filters eliminates possible chlorination-resistant bacteria, finally obtaining a clear water having a pleasant taste which is perfect for human consumption.
The deodorization and removal of the taste of the water is carried out with the help of activated carbon. However, the hardness of the calcium is reduced by interchanging or exchange resins, the effectiveness of which must be controlled and which is not readily recognized.
The regeneration of the ion exchange resins is carried out with diluted salt, restoring the softening properties of the water. The activated carbon is regenerated subjecting it to the action of heat in a furnace. However, the duration of the exchange resin, after a finite number of regenerations, coincides in practice with the duration of the activated carbon and in view of the low cost thereof, both components are simultaneously replaced thus to facilitate the handling and potential yield thereof, they are used in a combined form in the majority of the cases.
Thus, there remains the problem of determining exactly the exchange capacity of the resins, wherefore apparatus for measuring the electric conductivity, the effectiveness of which is doubtful in spite of the high cost thereof, are commonly used.